214 



SOUTHERN FIELD CROPS 



Fungous Diseases 



While the corn plant is subject to a few diseases, these 



are not known to cause much injury in the South, with 



the exception of those mentioned 



below, which injure chiefly the ear. 



195. Corn smut ( Ustilago may- 



dis) . — The presence of this disease 



is first shown by a large swelling 



on the ear, the stem, the tassel, or 



the leaf (Fig. 108). At first, this 



protruding mass is covered with a 



whitish skin, which later bursts, 



setting free clouds of black powder. 



These powdery particles are the 



spores, or bodies answering the 



Fig. 107. — The Indian purpose of seed, and Serving to 



Meal Moth. gpread the disease to the next year's 



The larvae injure corn. . 



Enlarged. (Photo by w, crop. These spores gam entrance 

 E. Hinds.) ^ ^jig young plant after it has 



appeared above ground. The spread of this disease is 

 due to smu,t masses left ip. the soil by a preceding corn 

 crop, or blown in by the wind from surroimding corn 

 fields. No treatment of the seed is effective. 



The method of spread of the disease suggests the means 

 of decreasing it in subsequent crops, by gathering and 

 burning the smut masses before the whitish skin breaks 

 and sets free the spores. On the same principle, rotation 

 of crops is advisable, especially if this results in growing 

 corn on land where no surrounding fields in the preceding 

 year matured smut spores. 



